#include "messagedigest.h"

#include <string.h>

#include "sslconfig.h"
#if SSL_USE_OPENSSL
#include "openssldigest.h"
#else
#include "md5digest.h"
#include "sha1digest.h"
#endif
#include "scoped_ptr.h"
#include "stringencode.h"

namespace base 
{

	// From RFC 4572.
	const char DIGEST_MD5[]     = "md5";
	const char DIGEST_SHA_1[]   = "sha-1";
	const char DIGEST_SHA_224[] = "sha-224";
	const char DIGEST_SHA_256[] = "sha-256";
	const char DIGEST_SHA_384[] = "sha-384";
	const char DIGEST_SHA_512[] = "sha-512";

	static const size_t kBlockSize = 64;  // valid for SHA-256 and down

	MessageDigest* MessageDigestFactory::Create(const std::string& alg) {
#if SSL_USE_OPENSSL
		MessageDigest* digest = new OpenSSLDigest(alg);
		if (digest->Size() == 0) {  // invalid algorithm
			delete digest;
			digest = NULL;
		}
		return digest;
#else
		MessageDigest* digest = NULL;
		if (alg == DIGEST_MD5) {
			digest = new Md5Digest();
		} else if (alg == DIGEST_SHA_1) {
			digest = new Sha1Digest();
		}
		return digest;
#endif
	}

	size_t ComputeDigest(MessageDigest* digest, const void* input, size_t in_len,
		void* output, size_t out_len) {
			digest->Update(input, in_len);
			return digest->Finish(output, out_len);
	}

	size_t ComputeDigest(const std::string& alg, const void* input, size_t in_len,
		void* output, size_t out_len) {
			scoped_ptr<MessageDigest> digest(MessageDigestFactory::Create(alg));
			return (digest) ?
				ComputeDigest(digest.get(), input, in_len, output, out_len) :
			0;
	}

	std::string ComputeDigest(MessageDigest* digest, const std::string& input) {
		scoped_array<char> output(new char[digest->Size()]);
		ComputeDigest(digest, input.data(), input.size(),
			output.get(), digest->Size());
		return hex_encode(output.get(), digest->Size());
	}

	bool ComputeDigest(const std::string& alg, const std::string& input,
		std::string* output) {
			scoped_ptr<MessageDigest> digest(MessageDigestFactory::Create(alg));
			if (!digest) {
				return false;
			}
			*output = ComputeDigest(digest.get(), input);
			return true;
	}

	std::string ComputeDigest(const std::string& alg, const std::string& input) {
		std::string output;
		ComputeDigest(alg, input, &output);
		return output;
	}

	// Compute a RFC 2104 HMAC: H(K XOR opad, H(K XOR ipad, text))
	size_t ComputeHmac(MessageDigest* digest,
		const void* key, size_t key_len,
		const void* input, size_t in_len,
		void* output, size_t out_len) {
			// We only handle algorithms with a 64-byte blocksize.
			// TODO: Add BlockSize() method to MessageDigest.
			size_t block_len = kBlockSize;
			if (digest->Size() > 32) {
				return 0;
			}
			// Copy the key to a block-sized buffer to simplify padding.
			// If the key is longer than a block, hash it and use the result instead.
			scoped_array<uint8> new_key(new uint8[block_len]);
			if (key_len > block_len) {
				ComputeDigest(digest, key, key_len, new_key.get(), block_len);
				memset(new_key.get() + digest->Size(), 0, block_len - digest->Size());
			} else {
				memcpy(new_key.get(), key, key_len);
				memset(new_key.get() + key_len, 0, block_len - key_len);
			}
			// Set up the padding from the key, salting appropriately for each padding.
			scoped_array<uint8> o_pad(new uint8[block_len]), i_pad(new uint8[block_len]);
			for (size_t i = 0; i < block_len; ++i) {
				o_pad[i] = 0x5c ^ new_key[i];
				i_pad[i] = 0x36 ^ new_key[i];
			}
			// Inner hash; hash the inner padding, and then the input buffer.
			scoped_array<uint8> inner(new uint8[digest->Size()]);
			digest->Update(i_pad.get(), block_len);
			digest->Update(input, in_len);
			digest->Finish(inner.get(), digest->Size());
			// Outer hash; hash the outer padding, and then the result of the inner hash.
			digest->Update(o_pad.get(), block_len);
			digest->Update(inner.get(), digest->Size());
			return digest->Finish(output, out_len);
	}

	size_t ComputeHmac(const std::string& alg, const void* key, size_t key_len,
		const void* input, size_t in_len,
		void* output, size_t out_len) {
			scoped_ptr<MessageDigest> digest(MessageDigestFactory::Create(alg));
			if (!digest) {
				return 0;
			}
			return ComputeHmac(digest.get(), key, key_len,
				input, in_len, output, out_len);
	}

	std::string ComputeHmac(MessageDigest* digest, const std::string& key,
		const std::string& input) {
			scoped_array<char> output(new char[digest->Size()]);
			ComputeHmac(digest, key.data(), key.size(),
				input.data(), input.size(), output.get(), digest->Size());
			return hex_encode(output.get(), digest->Size());
	}

	bool ComputeHmac(const std::string& alg, const std::string& key,
		const std::string& input, std::string* output) {
			scoped_ptr<MessageDigest> digest(MessageDigestFactory::Create(alg));
			if (!digest) {
				return false;
			}
			*output = ComputeHmac(digest.get(), key, input);
			return true;
	}

	std::string ComputeHmac(const std::string& alg, const std::string& key,
		const std::string& input) {
			std::string output;
			ComputeHmac(alg, key, input, &output);
			return output;
	}

}  // namespace base
